Micro-phase Separation Of Polypropylene Thermoplastic Elastomers

In order to prepare the polypropylene thermoplastic elastomer(PTPE) whose phase domain size was fine, morphology was easy to control and the overall mechanical properties was excellent, PTPE was synthesized in the homogeneous system by using "polymer-bridge conjunction, dynamic vulcanization, microphase separa tion" technique starting from ethylene -propylene (M) or styrene butadiene(N) and PP through a polymer-bridge conjunction derived from a monomer containing a carbonate group in the presence of a free radical initiator. The microphase separation was resulted from energy effect and morphology and dimension of phase domain were controlled by energy effect and entropy effect during process of reaction. PP would shrink owing to crystallization during cooling coacervation after reaction. As a result, the phases reversed, and PP with finer crystal was dispersed in elastomers which had three-dimensional network with definite wall thickness.Microphase separation polypropylene thermoplastic elastomer (MS-PTPE) had been prepared, which had the designed chemical and morphological structure and overall excellent mechanical properties. The chemical and morphological structure, mechanical properties, rheological properties, MFR etc were characterized.The results showed that:(1) For the MS-PTPE, the percent conversion of elastomers was high and that of PP was low. Most of the conversed elastomer and PP existed in the crosslinked form and the residual was graft copolymers. Grafting and bridging efficiencies of bridge agent were considerably high. The bridge agent most existed as bridge chains in crosslinked polymer, and the residual existed as branched chains grafted on elastomers and PP. The prepared MS-PTPE consisted of crosslinked polymers, graft copolymers, unreacted PP and unreacted elastomers. Therefore, it had not only high elasticity but also thermal plasticity at room temperature.(2) Regarding to the reaction system of PP/elastomers = 30/70 and M:N1= 80:20, the percent conversion of elastomer and PP and the content of crosslinked polymers increased gradually with an increase in initiator and bridge agent amount; The percent conversion of elastomers, PP and bridge agent were about 84.87%, 36.64% and 77.67% respectively, and the content of crosslinked polymers was about 62.32% as the amount of initiator and bridge agent were 2.00phr and 18.2phr respectively.(3) Initially the reaction system was homogeneous. The microphase separation occured to the certain extent of reaction. Elastomers with cellular structure(sausage structure) was dispersed phase containing some PP. The phases reversed due to cooling...